The Cat Shows Her Claws(1960)

Overview:

France under the Occupation. Executed for treason against the Resistance, Cora, code-named "La Chatte", was left for dead. Recovered and cared for by the Germans, Dr. von Hollwitz brainwashed her to control her and use her as a counter-espionage. In the spring of 1944, her escape was faked so that she could resume contact with the Resistance. She has to scupper the mission of Charles, an engineer with the SNCF, to blow up a train loaded with V1s intended to power the launch pads set up on the French coast to bomb London. But at the last moment, La Chatte regains her lucidity.